Front brake wear faster than rear?

JavaCofe

Hi,

I'm an avid all-season all-terrain cyclist with a Specialised Rockhopper Comp '11 with Avid Elixr hydraulic disc brakes. I've been riding for years but only had this bike since Sept and have just replaced front+rear pads. I immediately noticed the diff on the lever resistance which to me confirmed I was indeed overdue for replacement after just two months. I realise this is rather extreme but I do an 2.2mi urban 'sprint' twice daily to/from work then between 15-20mi religiously at weekend on the hills, so I think £30/yr on pads is fair for this use (plus I weigh 211lbs!)

I'm now 4 days 'into' the new pads and notice the fronts are worn much faster than my rears and I need to tug harder to get distributed force. I've no idea why the front would go faster since I only use it on level ground?

nicklouse

the front brake does most of the braking so it will work more and wear more.

The Rookie

The front will take about twice the brake force as the rear before lock up, as you have the same callipers and pistons and not a double the diameter disc, the front will take a lot more 'tug' as you put it....

You say the fronts are worn much faster than the rears, how are you deducing that? Are you measuring the remaining pad thickness?

Even at 211lbs I wouldn't expect you to need pads that often, I'm 180lbs and I've done 2000miles on my commuter on second hand pads with no need to change for the forseeable future, my MTB has done about 25-30 miles a week and the pads are like new 6 months after they went on, how did you deduce the pads needed changing? They only need changing if they are worn out (less than 1mm of material left) or contaminated, anything else is a setup issue!

Simon

JavaCofe

You say the fronts are worn much faster than the rears, how are you deducing that? Are you measuring the remaining pad thickness?

primarily by brake resistance at equal squeeze force, though maybe the fluid pressure on the fronts is less?

how did you deduce the pads needed changing?

I deduced it by almost running into the back of a car :P There was a definite limit to the stopping power so I couldn't enter burms at the normal speed and had to back off knowing the brakes couldn't rescue my ass..

The Rookie

Sounds like contaminated pads, unless they were worn down to the backplate - and I wonder if you've started on the fronts again, pad wear has no effect on braking right up until the point they are worn out (the metal backplate starts touching the disc) - were they worn right away?

Simon

DickBarton

Lack of power...I take it although your braking resistance differs between front and rear, you did squeeze harder on the front until it stopped?

Rear wheel as much less weight on it than the front when it comes to braking in a forward direction so is much easier to lock up...if you are braking properly, then your front pads should need replacing befroe the rears anyway...the front does the majority of stopping whereas the rear does slowing. Car brakes are the same, a lot of cars need new front pads long before the rear ones need changed.

I'd give them a bleed and see if that improves things...new pads might help but the initial use of the pads will be rubbish until they bed in. If you are replacing the pads, then make sure the rotor and caliper is nice and clean as well.

nicklouse

DickBarton wrote:

Lack of power
I'd give them a bleed and see if that improves things

a bleed will NEVER bring back power it will just remove a squishy feel to the lever.

if the OP has a squishz lever then a bleed may help if the other causes have been checked.#

A bleed is the LAST thing that should be done and is rarely needed.

JavaCofe

The Beginner wrote:

Sounds like contaminated pad,.. were they worn right away?

Simon

I did take a photo of one of the pads vs. new and noticed there was only a tiny sliver of resistance material left. I can't recall whether it was front/back but my novice head told me both were beyond optimal. Which is saying that I felt that after replacing them I'd be able to gain sufficient extra braking force that it'd be worth the cash - £2.50/set.

As for bleeding, I don't have the equip and although there is a bit more squish on the front it's still giving me enough range of motion to modulate between slowing/stopping.

The Rookie

Doesn't sound like it needs bleeding, not sure about buying pads at £2.50 a set mind you!

As for optimal, there is no optimal amount of material, any works as well as lots really (simplisticly before someone comes up with some unlikley example)
Simon

Russ-Tyson

JavaCofe wrote:

I'm now 4 days 'into' the new pads and notice the fronts are worn much faster than my rears and I need to tug harder to get distributed force. I've no idea why the front would go faster since I only use it on level ground?

How many miles have you done in the last 4 days?!! I run superstar Kevlar pads which aren't the most durable but give excellent braking,I have run the same pads for the last 3 months and have used about half the pads on the front....I weigh 235lb and run Saint 4 pots through the most muddy/sandy/wet conditions and they still brake the same full or half pad thickness.

I can only think that you have a contamination issue or just cheapo pads or just not bedded in yet.Try cleaning the disc with isopropyl alcohol and lightly sand the surface with wet and dry paper see if it helps.

The Northern Monkey

lol. I'm the opposite as I tend to drag the rear brake :oops:

bobbygloss

The Northern Monkey wrote:

lol. I'm the opposite as I tend to drag the rear brake :oops:

Glad it's not just me. I was reading this thinking I must be doing something seriously wrong. I'm on my 4th set of rear pads but only the second set of front ones (2500 miles on a front set, 1100, 1300 and 900 miles on the rear sets).
That's with Deore brakes, original resin Shimano pads and then sintered BBB pads.

bails87

Bobbygloss wrote:

The Northern Monkey wrote:

lol. I'm the opposite as I tend to drag the rear brake :oops:

Glad it's not just me. I was reading this thinking I must be doing something seriously wrong. I'm on my 4th set of rear pads but only the second set of front ones (2500 miles on a front set, 1100, 1300 and 900 miles on the rear sets).
That's with Deore brakes, original resin Shimano pads and then sintered BBB pads.

:shock:

I realised both my brake pads were essentially down to bare metal after ~300 miles the other week, those are OEM Formula pads.

DickBarton

Nick, you've taken 2 parts of my post and removed the inbetween bits which makes the statement sound rubbish...

Giving a bleed will help but it may not bring back power...I'd suggest making sure everything was properly clean and contaminant free - this doesn't mean free from mud, just free from oil/grease and stuff that generally doesn't help adhesion of braking surfaces.

My braking technique is shockingly bad...I know what I'm supposed to do but reality is completly different, saying that, I run Superstar Kevlar pads and the fronts are slightly more worn that then rears, but they seem to be pretty even and that is after about 9 months use (although admittedly hardly any real use!)...

spongtastic

Sintered or organic? Bedded in properly?

I forgot to toast a set of sintered avid pads and they were destroyed by a month of riding in sandy grit

bennett_346

spongtastic wrote:

I forgot to toast a set of sintered avid pads and they were destroyed by a month of riding in sandy grit

:shock:

Explain?

njee20

The disputed theory that one should always 'bed in' pads by getting them incredibly hot a few times before subjecting them to abrasive conditions.

I also tend to wear rears out quicker as I drag the back far more than I should.

I tend to find pads last months, and then disappear entirely in one really wet ride. I went through 2 sets of pads, the backing plate and some of the pistons in one 40 mile race last year.

Northwind

JavaCofe wrote:

As for bleeding, I don't have the equip and although there is a bit more squish on the front it's still giving me enough range of motion to modulate between slowing/stopping.

Saw a couple of comments like this in this thread... If your brakes are working right, worn pads shouldn't reduce braking power, almost all hydraulic brakes correct themselves for pad wear. Once a pad's worn out you can lose power- sometimes once the friction material's very thin it can start to break up a little, and of course once you're through to the back plate Bad Things occur. But a half-worn pad shouldn't give you less power or more "squish" than a new one.

cooldad

njee20 wrote:

The disputed theory that one should always 'bed in' pads by getting them incredibly hot a few times before subjecting them to abrasive conditions.I also tend to wear rears out quicker as I drag the back far more than I should.

I tend to find pads last months, and then disappear entirely in one really wet ride. I went through 2 sets of pads, the backing plate and some of the pistons in one 40 mile race last year.

Glad I'm not the only one. I just put them in and ride normally. Never had a problem.

The Rookie

I'll have a chat with the brakes guys at work, I know all our bake test cars have the pads 'bedded in' but I'm not sure if it's to 'improve' them or just to give a consistent starting point for testing!

Simon

386ka

cooldad wrote:

njee20 wrote:

The disputed theory that one should always 'bed in' pads by getting them incredibly hot a few times before subjecting them to abrasive conditions.I also tend to wear rears out quicker as I drag the back far more than I should.

I tend to find pads last months, and then disappear entirely in one really wet ride. I went through 2 sets of pads, the backing plate and some of the pistons in one 40 mile race last year.

Glad I'm not the only one. I just put them in and ride normally. Never had a problem.

This. I don't think bedding in really helps extend their lifetime, but just to start them gripping the rotor.